Video Transcript
A porcupine has 34 chromosomes in a
typical body cell. How many chromosomes would be in a
gamete, sex cell, produced by a porcupine?
This question asks us to determine
how many chromosomes would be present in the gametes of porcupines. To work this out, let’s first
define a few key terms. Typical body cells are often called
somatic cells. Somatic cells are diploid, which
means that they contain pairs of each chromosome and is often represented as two
n. Human somatic cells usually contain
46 chromosomes, 23 of which are gained from the biological mother, while 23 are
gained from the biological father.
Thankfully, the question gives us
the number of chromosomes found in a typical body cell of a porcupine: 34
chromosomes. As porcupines reproduce sexually,
half of these chromosomes would originate from the biological mother, and the other
half would be from the biological father, provided in their gametes, which are
otherwise known as sex cells.
Next, we need to discuss the
chromosomal relationship between typical body cells and gametes. Gametes are haploid cells. A haploid cell, which is often
represented as n, contains half the number of chromosomes as a somatic cell. When gametes from each parent fuse
together in fertilization, they form a cell with the full diploid number of
chromosomes. The gametes of the mother and
father porcupine are haploid as they are produced by a process called meiosis, which
involves two cellular divisions. Overall, meiosis produces four
haploid gametes, which contain half as many chromosomes as the one diploid cell that
produced them.
As we know that the genetic
information in a diploid cell is reduced by half in order to produce a haploid
gamete, we should be able to work out the number of chromosomes in a haploid cell by
dividing the diploid chromosome number by two. Remember, the diploid chromosome
number in porcupines is 34. Therefore, we are able to work out
the haploid number in porcupines by simply dividing 34 by two. This means that we have found the
correct answer to this question. The number of chromosomes that
would be found in a haploid gamete produced by a porcupine is 17 chromosomes.
